With increasing environmental consciousness, electric vehicles are gradually employed. Moreover, the electric vehicle is usually equipped with a charging device to charge the storage batteries of the electric vehicle. According to the type of the input power source, the charging device of the electric vehicle is classified into two types, i.e., a single-phase charging device and a three-phase charging device. The output power of the single-phase charging device is usually 3.6 kW or 7.2 kW. The output power of the three-phase charging device is usually 10 kW. As the endurance power of the electric vehicle is gradually increased, the level of the output power is also increased. Consequently, the high-power charging device is the mainstream of the market.
However, the conventional three-phase charging device is only able to receive the three-phase input power source to perform the charging operation. In case that the input power source of the charging station is the single-phase input power source, the charging operation cannot be performed on the electric vehicle. For solving this drawback, the electric vehicle with the three-phase charging device is equipped with a single-phase portable charger to provide the single-phase input power source to the three-phase charging device. However, the use of the single-phase portable charger reduces the electric safety and increases the cost.
As mentioned above, the conventional three-phase charging device uses the single-phase portable charger to receive the single-phase input power source. Generally, the three-phase charging device comprises three modules to convert the corresponding single-phase power of the three-phase input power source. While the three-phase charging device receives the single-phase power, only one module of the three-phase charging device is enabled. However, since the level of the output power from the single module is limited, the level of the output power is possibly unable to meet the practical requirements. For example, if the current of the input power is increased, the level of the output power is not correspondingly increased. In other words, the output power of the conventional three-phase charging device is limited.
Therefore, there is a need of providing an improved charging device and control method therefor in order to overcome the above drawbacks.